1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and, more particularly is suitably applied to a method of polishing a silicon oxide film using a silicon film as a stopper film in a chemical mechanical polishing (CMP) process.
2. Description of the Related Art
In a multilayer wiring process and a formation process for device isolation, a chemical mechanical polishing (CMP) method is often used as a process for planarizing a surface. In a device isolation structure, a stopper film is used to automatically detect timing for ending polishing. A silicon nitride film is often used as a material of the stopper film from a viewpoint of detection performance and a surface state after polishing.
For example, Japanese Patent Application Laid-Open No. 2008-226935 discloses a method of using a polysilicon film of a base as a stopper film without using a silicon nitride film.
However, in the method of using the silicon nitride film as the stopper film, because it is necessary to remove the silicon nitride film after a CMP process, the number of processes increases.
In the method disclosed in Japanese Patent Application Laid-Open No. 2008-226935, the surface of the polysilicon film is frequently rubbed by abrasive particles, scratches on the surface of the polysilicon film increase. When a device is manufactured by using the polysilicon film, deterioration in device performance is anticipated.